SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b17702bf6418f5acf04d6ac4632ae72981ab059a27e9298d98cb0b17bc0d8747' 
  AND token = 'Kxq8aKzj3Ca6Ju4PZ+FRreSVCbquEG8+AcL+WwB2vKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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