SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca4efaa1894ec51e08a15f8a93f25fc8c61966f31254daaeb4b3d2296cbe9f3d' 
  AND token = 'DXkS8xpEuyMTAiOO0YXbUcw92wIh96dmEDf1gfnFeUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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