SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a81f92cbe724d5b2097ac78dc76858ac482dd087e770c957a46be649681253f6' 
  AND token = 'sX/FYI0lodrEKQK61vfhH6X933/wwTictaMoWiTPG0k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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