SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da2a7618c60bc76a4914832ae9f28ebf514e5117f9fb020542492b9f78c39175' 
  AND token = 'nfuRbTC9IKMALOY4QxyRrIgckqdou0HdY+stxTNMXyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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