SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3b6b900b5c07dc127fea23fe836c968c390cc48fbcf8b005cc1caf5778217d90' 
  AND token = 'EYrINgmQkrRglr25zkAr8vh0nDIOzRODRmySn4rn+kc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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