SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a76fcda646f796ad635de72348a258121833240718f53b185343bf1ab3963872' 
  AND token = '7gvg/0otoG/RgxIlWhhdexPFPt9wjTCqjMYaNWCtdoE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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