SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0829df7dede47433ff3031aea2b9ffe3031237ed67fe4bbeb00f18affe2dba4b' 
  AND token = 'l5pm0jqihunWBr1NshJR0oxO8oF9wzshtj+eT78ip3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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