SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e29aec0d37ef2259549eeaa5c8264e414e203c21170e88785a8594b17267343' 
  AND token = '/cKPbHLe35U5WsKXFJuQTZGNlGyZDcvO/tasls3RoZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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