SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a61ea86ab7cfdde12e9e18986917e9c88a2c0d9c697076fdec27fc59e2e08634' 
  AND token = 'qQoiAxyfEPmOLdpirNtu0D5WM6fdINusRGv5ayiw3FM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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