SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c3308a409d5febaa1084da7bc99854d579854261dc92e1337426f88aa576b64' 
  AND token = '52MxIFb3E65nwR9YNXI1nbRyNddRSdvUjfmnU7VhYKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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