SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fb37083c8a53523fa42cd5c338f6568e248be28947703529d6870cea11af702' 
  AND token = 'SUibbb/lXuNqPwp2vDdT+yAVbCMv5TZEQjwH7n4l7fE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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