SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b40d755f8069c423e2d8fdac823c5386c1df52745a5c1129ab295823543c4bdd' 
  AND token = 'lgG2lx5DxvEAMDpkr6RsZv0QlkeyEzZ/LpwnyCdd0kY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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