SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3eb709997ee8bf7beddd74397cb61ff5521502ea21c107a0145e430adaaaf11b' 
  AND token = 'BIWSM9Tkeu2hha1JtXedRlWNvmBxtSsLs6nZm1O1Wgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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