SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12e7f0dbff9fdb17651258cce8d8a1362931726d20a023ab869426b0408c1d13' 
  AND token = 'mwkEJOJfCQHcTVa/xrOF9XVpAD5deXlcIYyqzho+6CM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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