SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bcc5e85961616e2c5c1ad426a3a17d3d754f5663f44fc149083cdd55d6b6e2bb' 
  AND token = '5tSmgFm2eRvCzB/zVTUjFUrdFSmHo1pS0cxXYUJq6Us=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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