SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '903e40417ef70222ef327d138c6f348124a67c499490a6a18bff88d8ec37a457' 
  AND token = '0JF0Dk2ttzZ3z/wn20ou9w+PhK6XIM9UyU+YUSjgj1A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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