SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2f271e0934abc628a0a7607c48fa43b5e4fd11171b2a03baf84acdf81dfc380' 
  AND token = '5dYTQhfEk+7zSCcmSF0RTd5RclwUoF3nCPETR9UbU/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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