SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fe2e90923824e607164d0d5820b768253a8d83069e17630c29f9eb1fb5e1c6c5' 
  AND token = 'iyvOKMajrs7z16HgODhVbY3y6EhYWcXi1IwIiDBw1qk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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