SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '868415d5b29801cfcad9a06cd9a576ef252e4d69f8584205ffff55e7dd0b5457' 
  AND token = 'GBs/clC3ryfJpoi6wseeBZ8oPGuQSgvjhD3mpPQ/Jos=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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