SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d456b10750667390dab0440f81869168ff4e320124a2f57afc546eab05a2ee8' 
  AND token = 'MqxQfsD+NT69Ke0q8XsnBWreK0c4w30Rdxfsjh3/vZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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