SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7878fba8463c88ad8e2cefb732edd12b394dc3718c57ecd128e5350d8d046306' 
  AND token = '6DcuJ4hQ7y6qIh72R4RhN+XP1RziA0Pq4tNoqOIrE8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}