SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14fd75e0a27af186a3399438ae913748ccc3b0269d0cfdc7b689d839ac9c8be8' 
  AND token = 'fAJ4jmHAA+aK0ksvKZG9NATYAgTN9P5oNEYY4ybzrgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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