SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6aaba3217bdd46fea18a7a788ee057fb38351da6dc2c066e58aa14d5c52a9fb' 
  AND token = '2C4IicLvPxiT60PvaN/eiSXqEGkzYDmew8NFuC6c1CU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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