SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc35f952dbfd22fb56155c23fed0e9963bb432496d38e2bcb2c1d87a84235c36' 
  AND token = 'n3LvZlMxt+NNjml8FrCg5XQ3OiQQplaNMI2GOJpxTSQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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