SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0161517304fc42279e57c9ba957f3d99fde2be57c5c24373a157374038df872a' 
  AND token = '4CHNhZ3SlaQBOzgkLFE6vfySw8VVYnvMOiZhbWYt94w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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