SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '04600ef219b7bc8ecb7de78e918ade09bf9463c13ca81af527f92eecdc418c3f' 
  AND token = '0uorBuyDhGnqZGbxzRDgYQAHEgDLZVtbAFdHb/1DluM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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