SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a09b5665e04245980a9e698cd96f4a5bce77f03a8d6c55416ad2f1171f9bf71c' 
  AND token = 'OnT5TTdxGomXMK8AwXFXQSnwJf4cCgzI92oQHc3+gAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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