SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '818abe2eff402d52740f42535ca96ffbbb34a2eba63aa2e7628c998bb3ac10d1' 
  AND token = 'nenm+ZqLguOAbLEIQgsHJn2Y4C21yRGU246JXLHHQ9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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