SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '739aa26f701681d9452245266f08b22fc5f2a8bdf76d694e767a10b5234e2d52' 
  AND token = 'RgUtQNbTmyOBJMe6DMB4g7HeHJ6AUbXyw+tW2E8ltjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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