SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c40bf0253cafc5add51b5235197470e92c59fd7362c53fd98ba731683bd95460' 
  AND token = '+CVygVPFg/qXMyxa5+owxizu3CkXFQ9bunTmQY4RU94=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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