SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d9b32d5ca64c3a684e77cbfddae0b4b8a08953926271fe9c80fd26e05b0b692' 
  AND token = 'ncy7PTFjVKsBda+9nCnzYaZ3Kz/735tEuVI4GxOorgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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