SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff2072c24e84c9139cabca860aaf940b009fb83b66977b83e3dba41a60f0ffb8' 
  AND token = 'SZSjgSGOz81CjKxYMndGn/5mk84//o0zVCoc2dwpzII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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