SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75f7660f5dfff37173c4967ac0a44cc9cbebbce7dedcea2bbe9660dc2e5d15fb' 
  AND token = 'aaAa7blfRgGiu8ou0m8RE36IqTvOMOa3lh+tv1bh55I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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