SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d12ade585df2134a6e8b449362e877970375270df7bd6ad82da706e25c20390' 
  AND token = 'PCy4eiY1ntBB34EwwWvGMeUDB1oq7Heyh3rMh0Lfz6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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