SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '348b0b7d6bdfc7d0b56d2369f324ebcc76dd273f2375fff392837d14d83b6873' 
  AND token = 'JbVEyFf8Z45J+doSxn4LSgJvFiVL/laIePzl5RBjqQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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