SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3491dcf06bb1718e775382e6f21e4d8291668e341e0cb26d4b2bc1ba67accf78' 
  AND token = '8JAn02jvzd+BRWw84pF4WvXPDuPfT+5ZoYwc3MlDRmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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