SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2376a0099b0664d94853b747d7d144cff19e1dd548c48e9f5790edacb4490ff6' 
  AND token = '5jKnxOaLQwVoZ9/0zQ8KvhNlPqhsl505mgGQRMeSma0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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