SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '492f15ff6ece0f3cc54a3994a671e755be2abb743022138e3070c4a4700d876f' 
  AND token = 'QKVZofhbXjrWe887kI/TQn24gmo2DRp5yi3YOmqCIpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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