SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c608060e35cb344946536746428d48140ed2acb916495329b9be56c03afe558' 
  AND token = '76Fli42URXLVVEQiqgMujnoXT/Ja1xnByQ/C9qfu7lA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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