SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '609e29f86460a1e2bef79b0cc2e7578a737fb115abadf34893cb9b33de05e48d' 
  AND token = 'f/MBnCKSU/AIonoJ0EFUypYZCpeTwyAIbIr1IoiCf7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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