SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'abfc1193a8c2c3bcf2de636006a2668d459a2554a2616858848bba5995f360ff' 
  AND token = '6RQKAF853sQqJis3oPbZXiRyZgDCU+FghN9qwpnTd40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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