SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a57fbbed57fd66524a3a2fcf12bafd905886139f04e654b3e6496d267528c36f' 
  AND token = 'jVgXW1VmhZCEkBsxcnLsNgENc+T8EhIdqihTsjZsvDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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