SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a08fc694d1c7f5bcb99b01ba48b10b0f225bd230f1da01e7f3e23e57f290be2c' 
  AND token = 'mLFuuXID8HfY6r4Pfynx3neGBff0yl4VYgNQ8qlp4Rc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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