SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a08c0500275925b9c0f551b53665152722f57acd7b2e839f9da55435511e557' 
  AND token = 'uqz5Jpsjg7P0QoEFHvQBMiPguN15RkuA95qnzVJDSC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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