SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15746318254fae888c7ed24fc15674d1cfa836fc855a58763719144500c169e7' 
  AND token = 'yqMoNHGgrGfoC+fkDPUWSYZzFefmahVMPkoUXPS40Sc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}