SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e27e1d93ce2abef412131d02d19c04c4186bb843b911d2135a812bfac67a0e0c' 
  AND token = 'gAPTPw+OBFGDvRYD6WsOhyZZF+k48ku24iFIBXRepRY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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