SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5c39281bfb6c5d749194b888ac81e361a2ebd720584586acb9313b3f1734e6d' 
  AND token = 'z6/tccETvOxscQUk2KEcxxqsafOGdOagQLVfF4sczrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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