SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34e426e0e52a454117d7bfd1f4630b09b527cac40894847f4f1ade85d21f1da6' 
  AND token = 'ZQDv+CNtrC83HuhfxTmeHRiwxJHoriVwM5uB4vGoD58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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