SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '210b7a29031824744425fbe8ea4d0a8a750cde1ef4ff42eff78d823e8609f4c1' 
  AND token = 'eT7qoWlYtYGg8TgxWFOUQrzYPLRElD5KiJ5eq8EXBtI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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