SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '78250546fd69a8575e6e781678d5a69fc47c4836a03fc247bbfb6ab6a3a98d68' 
  AND token = 'h8bWRmfsXGj89fZV65qDyEYh85YSh4XSB+UPppDpqA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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