SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '893aa355fe28ff7b9fc13a4809eff84037a6781d4f8f95003cf3c304651ad7fd' 
  AND token = 'i5UU3YXcj3oWxsCRRDIvfdhnXW0j5rbZ6iWbvBy2s8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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