SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ef2f429723c80b57ba9a15a05d6e395ccddc59bdc25bfa33caafe1b9ff3c3c8' 
  AND token = '2kTzeXEBMo2q5nqGn3Cw8mcfJJ4uyAIbPECEJeVyViw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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