SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f2c3dbfe6b431c9717e60847867f285ae2b17d642be8f540aec7dc98dd89cde4' 
  AND token = 'cZtFhckw1VvsXWJ3hjmogVfWO2SHJCS1W8xron+rnQc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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