SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df8fb765ad71c7316624c1426f89ee13a417e18683e5ed8caf2e192b713e0c63' 
  AND token = 'Z5e3mgYP4nbjxzyh0iKIqhRGEv0D8OAuVXQGLDi6OoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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