SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4d20ef45a91ce54758eec9e3412a81d201d7fb1fc5752b55978c3a7bc652055' 
  AND token = 'ImHYyvQckTMX4X3crbbMikTBBg6HkSeJfDYCSg6lYT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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