SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4743292adba8a813820e25230904ed5c26cd87cfa2d4da1f42eb1c68d72f299b' 
  AND token = 'zWBXFRMQiGQ7Tqs0k4ZcjBivqZivtt+bGMCoPwVhPAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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