SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '139aaece11cf45403c8c9fcbd456c5d7b0e13a9882f3bac92b28a2c05c509aa1' 
  AND token = 'WmbuFmWeUGGP/iWgPYvz3mVCv3dC7K7lMIeg4UvfGak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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