SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '884e07a814da85bf78e6edd890a8b0345cab71090c6d8a97acb0216b296e3b68' 
  AND token = 'GwpMtxaTWTFZCiK+eESuVeRXSI4bufDeDjqlfsHN5PQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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