SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2b257ca286cc1bc730c3a26d0ef0ad0ab3cc494c72b1f967fa6d787d979c0b2' 
  AND token = 'tBurRHscYNFVFqFTQDBpfYgsaXP3bHveGF6BrDLf79M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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