SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b8bfada9be94d67477119640df852510a84f04f90b5a1a5eca3ce5a91764677' 
  AND token = 'rcw9Lsnap/tRqjYroXn9fL/K9/jFz5kjUsUufItbXYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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