SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0391b59ce12c0713ed15e382bed82d45f52264705156f8503cfa3f57591d0a04' 
  AND token = 'dXNhKSfBwkvsJDkiEhRTD4chv5EmOzmWQPKUn708guA=' 
  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"
    }
  }
}