SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37c53dacfc02531b9f2d5d00b1e68bc1e949012882cafc65889c05d3a021ed6b' 
  AND token = 'DeTHnmzmq9RSuWcLkKbMSE0ySHgavNtmEA/fj/wmRBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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