SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89f90175e8cbe272deb3532703baee444bbf1eb6a24c19ad7320026278a43b3d' 
  AND token = '/3r6fhBgp7OrATdNCkCWtmpxtGPCclTYMLwEaDvT4fE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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