SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ca3318ff21849190860808ec3e12c66fe6de9be943e16aead046525ac697bdc' 
  AND token = 'OcGsvKHtCm/4XVPCLBtgcg/bYq/ilS8BulRQsP9rJws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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