SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6589c507f8abf4a07bb5b8cf70416a2e5d9bca938c025c5396dc3936f32c3747' 
  AND token = 'OQvOODx4hvEK4Rg8MazjzSxwDmgXDRAEyaxGyRTFY+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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