SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1dc9474a72d4a3f3cc4ec52c4414a530b4b5eab45fd7469221900f861659983' 
  AND token = 'O/A5DHzMem2ZeMCnBnlwVR+Sdr6JCf4qMjNeVXL9I8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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