SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dedb98d2508654a81651db35d867376cef0a00b21827a4936ed40852332fb12a' 
  AND token = 'w4BNnyoB01SWLhr4iBtueKobpsMU9SPMuiK7zarjS30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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