SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4628440a7e992a54952d80f3e36f9f6c6f6ecb834534b314b751aa268b876f27' 
  AND token = 'uiHCwtuXpm+j4bRdK3CR69JsGOoLhFwGytS8E0ivCl8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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