SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ab73c70b8303d33035f07e272f805818d6d39b58b76b14f8a4c861402853189' 
  AND token = '1m2GUqkNpaNfoJ7dRdW+OF9InFLN9qRU6jmgqBYiMkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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