SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77985408b312e3e0f80dea64cf83e0989e5a428b51ec30c0a9b870fd4114f79f' 
  AND token = '4xdDihklSCpEYyuTxsR7vHsEi50b/UX5Z+EiZTx5G2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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