SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '947d1ff8fdf4360120a57f58c69261eeb7e4fb9f252799ed800c717d75329c28' 
  AND token = 'IXERK3PyKE+F3Kb78lujfblsPGcdBtIypJOpZzDjKQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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