SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '24a7361bb9b8a2e555d7893fb91c7cfd12af17271820198c48ae6342bd34ff48' 
  AND token = 'ovHfOpwLZkhkP0AV5kmwBLjNwMAi7KMfLrfgwutP1b0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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