SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08663181645668284e76e92a44a01545f40095ec52533cebcd451fb7ae2ac19f' 
  AND token = 'PxED7OQkNDbUTwxKm+swPSjonyZ2pSEb+tM+cbzwumI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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