SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f886826e8d9198c6b4e5b10d7c28da328af1d04516fe6dbd15ed3432f98c06ad' 
  AND token = 'scvZQjJVihJTIEaQ8ufKMWtrBhg18WwC7bOY/ArV4i0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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