SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a498746d741ed248d70d43f762539ef7ed6dd45dba66d02d2f3ecbf6039fa830' 
  AND token = '2+VTZwLC/15ymiGKTRMkixqsQxrK4CLpohfnGUmz6zo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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