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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e509732be1d520df18a2fa8dbd83fa825869b9a6020b932ba4a05e23fee3eb35' 
  AND token = 'p9jlFOgZuP+Z9HopWvxCI4rHeb0c+vbRX39NBa6WkOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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