SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd26679cca3cd1b82ef45383bfc9192d06f0b8933377c1900fd3a1ec765c857bf' 
  AND token = 'dFv/XiTT28fUuXJfYwwuaYXnmBZ9Vez/+3TFtnkqtJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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