SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8836770ceb0767b7741cb0af66fc8342841e5e69378492ac339443b564d7c697' 
  AND token = '4v/blVWxMgE9MO5vui+/MqCh7Tr+rHnxo3Z8eh5PCxc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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