SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc395ec889c45c7f42f8be72bc10b47406befd71bcf1c48fe65d2dda6b8cb250' 
  AND token = 'eHhYAFNzF+bhi3m/X1g6cGRRPKavBdAYDkg/+thFtVk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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