SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7444472184ad8085c094281b479ba8727bc2e59508ecccb1543c0817f0f5a349' 
  AND token = '+0UU4bP9apMQzajSwD9fhNorEPoKxDHDWHmTaFB8MXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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