SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4b7621ef3d74149924242a7ebd2b38215284e6a0cf5303f740d342aab6b2947' 
  AND token = 'FWzfiYVf517+buYvUFuUJiQ5Mdqbxr2AAnLMLrJouQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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