SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64fd808509ff6272a2a9ad375d875215b3508c7a8ac419b61d6b03845f3d3b53' 
  AND token = 'SrdjmWXixdYQzWmWHHP7wxvajIYAPAlbRpUsKmTpfnk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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