SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bbc2d0a6abbed2bb59fd3589ec7dec389fca259a57d73e6344407c2540e21fa8' 
  AND token = 'RmRtaac0rJzrY0IXlDU1Qs8kIrvGiH8Jsc2DmbQk7Zo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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