SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3883ff8ac69932b465b15948b9b4151cd4bd6d4760e1e0b9734480fd2aed2f5e' 
  AND token = 'PqUvTJZ7BEOskwh8einGVc08oPSnAR1z6/xXEgWo2kQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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