SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4f883e434fb9af852e469e2b172a9b39a303b2d9e56e03fa76165b8e2cc5242' 
  AND token = 'r80J6gnfKVhou/JT3WTONn8NdE/P9aW6EkTj4iVjdrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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