SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bee793f73ec77021e19865ac584c60815cf84d7f5c65e6a14f438a8013b3d881' 
  AND token = 'z/oT0ZIBdAGl83OsmCwMgmGlYf2KvlI+TKHbXAKf+E4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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