SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9b9bfde28e8eec13afbabef1947fb010982646100e3d7c7a36d116157a688d9' 
  AND token = 'FM3UgJDp7g4ROlKP9MY5YBqLS0DudFoICzGA/dzAc/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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