SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2648f93f1ad3cea2a5bfdc6c9bb3ba38ad7cfa549147f8689056c197b479bb4c' 
  AND token = '8eb4NEQCmN6/Wc12i19xTcNjhunL6Y2WvUo7YwOKEd0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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