SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '492d528b0e2cb7913e4070cf5c5395395a18e0b019cd0cf6198123b37fd39132' 
  AND token = 'RkLhktdZ1WH93SGLrLYc23aWB2Ex+gNyQoSKqZ3jI2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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