SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f9a51e78d680ff8daa702c21cc1fe0cd26ac9eeca923562819c165e671850de' 
  AND token = 'eoAHrPm4iogcDCeBOpXa6GpgR+HULAgJz0DcMEMLzs0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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