SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3aba8064d63433ee358c42331f25e007b15204c38fa7a19eed8d79152ab0a7b3' 
  AND token = 'zuEhaiQE3yyieJplUK541M9crWcsRuxeXiMLPOgzmM8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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