SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6b1eb0e4a8db0e307ce8726f690b20d8ae7eac88aa37768174a7cbc57a94dac' 
  AND token = 'HKYdikLhO+bVNpiBElEwp104mOgiKlAiBYd+wdvljYc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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