SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bdb8b866550036d7268e57cd83f6fa1ff5598a77c24259116d4dbce72465f6a5' 
  AND token = 'm+sfAj5uPnVLJhD9bxg/JxqS+ACy0hJrU7a9rZ/ViNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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