SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a23a0c3828292d3e10efa3b79ed41e57e3d8d4159778617749148051270102c' 
  AND token = 'lxyU+uGV9IhYZpnBbBrSozl28khxAbptXFCisgJsvY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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