SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'deaa341a629458e3e9379651024dab09246c640a4bfe96f2156d8d561d7f273e' 
  AND token = 'Jwwgu5VnMBvgyp4XZD3nb4Q6TVvdDJbqHiBfYjh4K6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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