SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3400f1b20eae751edd7a74e4823404d41e9ed6f528815d83aa4f5797c7830a4' 
  AND token = 'NbX2EwDKqdteI/U+hmgwb1hbqsWRINLL/AbxXpU7bsQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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