SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8878add16a0347919be3fbc8db0a2e6867b89bebd355c2f76f7c803165685f5' 
  AND token = 'pr92354tHUuZXJ0n0JjaTr2UoLDM2COTRuyUaOoUeuU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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