SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e9b82d3c5d1ffef464812d5c52bc6e55e9cd93d649652b8706a8418ce2347a2' 
  AND token = '3HgyXcVzqmSPvhR7lqRPC4QVdteEJJwEWxqSiKw2Rds=' 
  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"
    }
  }
}