SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7be76e1eb18105ceb7d61eaf2ef813a577274ee698dcaa0a4a65f72d3c647f85' 
  AND token = 'PNqkKit43qj7RfZuvPnHj7Sf2s8hEA0gErkZmUhQ1N8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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