SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '286694be5a95f5051be1ed58033f2962fdd02490d83a55258926bba7643b0a74' 
  AND token = 'ZkwvMKChLu5qSs3SIxS5TYvJxDxZDBSuPJkIl6u9uKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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