SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9fd3d6f20754f6d327a20b1025fa60dcd4b24c6eb875d0ff8a2759d34e3a99c' 
  AND token = '6VhF9HmslDHUqFfY0zU7rGu+geqIfvBzpvFxdFZHIsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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