SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1f52113855a6d24d42b48140b77f2396d60a7b68209c22f737e89aca1544c13' 
  AND token = 'v6s6Imx9+uptdhjXZRr2vnEvAjuR4gN8+/PzDCVdkVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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