SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '764ef949f93a99e6d175f56302247e91c902de0f446de6c121235adb40224086' 
  AND token = '9kiEB+ZZE5BjvVGJ/NqbDACsxWNveSNiYAZSxKS8h18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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