SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2cb88f3649e4e91d9cd61cbf2ace3498a79650a4be951d7d6761a2701cd6600' 
  AND token = 'yfZKeuzJ+N6iH+6MFUOx8Vr8haP4D2lQU3btWbp7Tz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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