SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b41f736fec8ca09aab668c2d5b38d5e76a7e8cef87cafbab68fc652acc965900' 
  AND token = 'B/lu9Yl/b2lQDG9zTHl5vKI4I1hjYBLXMuOLG+t88/Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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