SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '29922991486cbe55a98363d68a63e4887790b716e6bf005678aadd80f723b347' 
  AND token = 'LuO+gABxNfMkhQ1XJNuwSq5njWhjHT74zIxeWVN2xy8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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