SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fab786cf5cdf8484b2cc607a6a28b9566a5871b58c58058110be4d90d43b0fd3' 
  AND token = 'zj7lJNZw+/n7VTui1mHAcZ2zTR4Y0GrLA3RONcQO+5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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