SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f6b3863b692282ae087c3f8c9360d60c8b39d10993d0d483be0f203e45e61e66' 
  AND token = 'KiZIaWydwz0xSzXjrIG+cVQAVqz32C9ME+ukfkRwmes=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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