SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '893486d46aa6ea869fb8618473758f700608ded1c0869c1015b0f1e70316aca4' 
  AND token = '/6dTlNLgTdzpOKmfJ6wpWb/Z8cXXakuIQr8/mnWX47c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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