SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e17ba4208540212e2b5edd4e3c8aa3edc5c35e0fef6d42a2bb06869a1d0375bc' 
  AND token = 'qDNclcxDBpXtDO7uUkRadbDuDEwnAOrpGNWe982Pggg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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