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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '421e008dc4b4b6eba9c400d8979ff26c41fac0bfb2690783b0f122ca6913ab07' 
  AND token = '0FBmoJKkil/Mf4sv5bObKe5RC01IGu7TiCcMTjSEVp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}