SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f983d22d076a91eef746b7da8aade13476107ec99a7ca7b64a7af1b7914e39f' 
  AND token = 'phr/DdRacpU0o8TsCLoFYbjElONKayOlJK21WFQd1fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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