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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3842460c52c6eb7d7239ebf972a074b9542eeddfe66bb77d4dd48db6d4368ff3' 
  AND token = 'hU6X3GpxLn5cFUzKi7IyOb11OZj5wu2E5mlWuS2Xu6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}