SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75fc14182d6e561c29135bad373a3fc4fe6cd0bde4586bd066ea853cfbcc1d23' 
  AND token = 'IMeDPkEiq8T0KpO9GZvXSiibvxHWq6VawaK4/qymZf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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