SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68638e53e5cfc55510f993fcff4ad776976b6a7dddac857b2174f6c4f23eba7c' 
  AND token = '0SNL2sLGRXeD+uX/2JUPq9xDxIK7mnl/gw5U+KAK6hg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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