SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9098ad15b4de3c5e42fbd6ec66528fc03c39962dd2bf8eace7d3805f71eedf63' 
  AND token = 'fdm+BPBrwcqQgsAUp/ARBCNl8pmEXOwiKSvGvL7Ne0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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