SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '361505453b68f94088f41f03123970c1a1dab41d3d3e83a636f44d7839df00f2' 
  AND token = 'W5/zrayzeeRwvfRs4PYwE+WAEYXlKs1f33eEWY8jVeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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