SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81656ca7c194fab94ba8813dc602c40abf97186b7e1811268251c933374b2959' 
  AND token = 'lSe6u/jdewW0TLDS6EDc9TXabFlpHNTiNdD6tldDSXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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