SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a975d0fb7f3e1ac077a38518c6767e728f8461f94a84d12c3ed0ef0bc35e22e5' 
  AND token = 'IZyw+HT3HurS+FzGBHH5TLsLnjhgKhAhyZWoIAuhSUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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