SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91eb3fc78634c073556b760d03b3244c43c8a1628f7c7bd293af025f5435c367' 
  AND token = 'CgzCFOByL0CmBMe2yCdOMjsUXwVsXvfGzTqQHAjDkLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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