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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f76fbdc3e233eba3aa0cb6d547068a3ba57e236a7f3d9f94545fb6ff62b4cf2' 
  AND token = 'Dexk42BnnfdYQIY4Gb5q/GSjRsGcrLd8lS6Z2UIMyrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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