SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e453b23f41500001501edbc7f019a1e7248b56f45e914840815de7eff124abcd' 
  AND token = '2+Ghp7lJb53H1MoL2tOFVcIP3rrcRnt8XrNbGXdrL+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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