SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6c77b82da80392dbfefe6ba80a213ae372033c2ca395778a29bb3c45bf92c49' 
  AND token = '7LGNDPPt39A2BTT+bT2RRZLDitUWBs3r86VYqcjRohA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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