SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe4af6b9cb305ee957b25046f3737c903e087f4951fd8763fa1cc0f1a040f23d' 
  AND token = '/bCd3B7ii7P+G5Aq4+rxgut44NJ8mRwCUI6WR9ST0d4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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