SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e849b8e7c311513e524f9cb765337af7898daee0e821d90efe04dcdf82f7afa' 
  AND token = 'ZcCkWYrgMQ+8q/6W1REJ76ziyKCM8+rVd9sJGbTtiNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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