SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '707ac22e596aa8563ebf023b55a13d00c6f3911484abc921bef727742de07ed6' 
  AND token = 'eG4z6hh2yH7eV5Y8FCgX7I3VUDRzWMDEhOcsupvpkWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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