SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e842900ca21fd857605792f5a6d510eac9e775137cb8ecfdd95712a80368694a' 
  AND token = 'kLASq+YabJ/pJ/BY45hGApXG4CsXyNsmJegHngWBnKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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