SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '486b9699087c08215760871c6cee76c1f850d437225e9438fd56cb0c1f38f197' 
  AND token = 'jCP+XLH9ZS79BSGrZagJx4LtLzqWjd27NWwAZvkkZXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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