SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c484d516dea98ac3a1c42cc3c871aeee7e607eab97bbc684f7fb10844e4d69b' 
  AND token = 'DSFqmOTJyf6vCWKXnoDp4kpvEPdSTpAcT03hWLwgKKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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