SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6ff259857fe621d6e06d4686899e0b97c453b38b4341d0c245e7de05d176afd' 
  AND token = 'ojLVp0VCABFSDmlmFs65sz/9XUJ08FTK3OlVkp4yhgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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