SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5e667298ea7827e888ba22688057d9cabfc2bfb5661c2dda85fbf25b63993e9' 
  AND token = '5uUIrSU0iepCdF+wpQcAcLJBQlAeMayawYOtRf37EN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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