SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8990198effa311cb3b05341ae7712b8ed43b40e71672c9850624336b0b50ac0' 
  AND token = 'a7cAKAWpHMhoDZVNIZdnH8+3FtJCAKKB9em6kzx4FnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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