SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6a268487ed3513c500514ea596034c8cb080c863399c9a76d6eb23588780ae0' 
  AND token = 'U0Yj12I2KfZxjvNy2E7FWWjS/MuMwDSB3DOySXtZ97w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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